JP2000007862A - Resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a resin composition comprising a specific block copolymer mixture and a styrenic resin and having a good gel level and an excellent physical property balance. SOLUTION: This resin composition comprises (A) a block copolymer mixture comprising block copolymers having at least two vinyl aromatic hydrocarbon polymer blocks and at least one polymer block consisting mainly of a conjugated diene and (B) a styrenic resin in a weight ratio of 5/95 to 70/30. The component A has a vinyl aromatic hydrocarbon content of 65-85 wt.%, a conjugated diene content of 35-15 wt.%, a number-average mol.wt. of 50,000-300,000, and a weight- average mol.wt./number-average mol.wt. of 1.2-2.5. The vinyl aromatic hydrocarbon content of the block copolymer constituting the block copolymer mixture has a composition distribution wherein the vinyl aromatic hydrocarbon content continuously increases within equations I and II [B is the vinyl aromatic hydrocarbon content (wt.%) of the block copolymer having a mol.wt. of M in the component A; BO is the vinyl aromatic hydrocarbon content (wt.%) of the component A; M is the mol.wt. of the block copolymer], as the mol.wt. of 70,000-300,000 increases.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition having less gel in a film and having excellent film properties.

[0002]

2. Description of the Related Art A block copolymer comprising a vinyl aromatic hydrocarbon and a conjugated diene having a relatively high content of a vinyl aromatic hydrocarbon is used for injection molding by utilizing properties such as transparency and impact resistance. It is used for extrusion molding of sheets and films. Conventionally, to improve mechanical properties such as transparency and impact resistance, a block copolymer comprising a number of vinyl aromatic hydrocarbons and a conjugated diene and a production method,
Alternatively, the composition has been proposed. For example, JP
JP-A-58788 discloses a branched block copolymer in which a catalyst is divided and added for the purpose of improving transparency and impact resistance, and JP-A-58-141233 discloses an appearance characteristic such as transparency and surface gloss. In order to obtain a thermoplastic polymer composition having excellent impact resistance, a composition of a thermoplastic resin and a block copolymer mixture having a composition distribution that changes with an increase in molecular weight is disclosed in JP-A-4-277509. In order to improve environmental stress cracking, a method for producing a gradually modified block copolymer in which a catalyst is divided and added is disclosed in JP-A-63-145314.
A method for producing a block copolymer having a B / S-S2 structure is disclosed in Japanese Patent Application Laid-Open No. 7-97418. In order to improve transparency, impact resistance, and reinforcing properties of a vinyl aromatic hydrocarbon polymer, a block rate, It describes a block copolymer characterized by the arrangement of the polymer blocks, the ratio of the conjugated diene in the random copolymerized portion of the vinyl aromatic hydrocarbon and the conjugated diene, and the like. However, when these block copolymers or block copolymer mixtures are formed into relatively thin sheets and film molded products of the styrene resin composition, the gel level (fish eye) and the physical properties such as strength and elongation in the molded products are obtained. Are not well balanced and these documents do not disclose anything about how to improve them and still point to problems in the market.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a styrenic resin composition having a good gel level (fish eye) and an excellent balance of physical properties.

[0004]

SUMMARY OF THE INVENTION The present invention provides a fisheye by controlling the composition distribution of the block copolymer constituting the block copolymer mixture by controlling the molecular weight distribution of the block copolymer mixture to be relatively large. It has been found that it is possible to obtain a molded article having significantly reduced (hereinafter referred to as FE).

That is, (I) a block copolymer mixture composed of a block copolymer having at least two vinyl aromatic hydrocarbon polymer blocks and at least one polymer block mainly composed of a conjugated diene; The vinyl aromatic hydrocarbon content of the polymer mixture is 65
Weight% to 85 weight%, conjugated diene content is 35 weight% to
15% by weight, the number average molecular weight is 50,000 to 300,000, the ratio of the weight average molecular weight to the number average molecular weight is in the range of 1.2 to 2.5, and the block constituting the block copolymer mixture The vinyl aromatic hydrocarbon content of the copolymer is 70,000 to 3
A block copolymer mixture characterized by having a composition distribution such that it continuously increases within the range of formulas (1) and (2) with an increase in molecular weight in the range of 10,000, and (1) B = BO (−0.47 + 1.6 × 10 ⁻⁵ × M−
5.5 × 10 ⁻¹¹ × M ² + 6.4 × 10 ⁻¹⁷ × M ³ ) (2) B = BO (0.28 + 1.3 × 10 ⁻⁵ × M−5)
6 × 10 ⁻¹¹ × M ² + 8.2 × 10 ⁻¹⁷ × M ³ ) (B: vinyl aromatic hydrocarbon content (% by weight) of the block copolymer having a molecular weight of M constituting the block copolymer mixture , BO: vinyl aromatic hydrocarbon content (% by weight) of the block copolymer mixture, M: molecular weight of the block copolymer constituting the block copolymer mixture) (II) a styrene resin; ) And (II)
Is a resin composition having a weight ratio of 5/95 to 70/30. Hereinafter, the present invention will be described in detail.

The block copolymer used in the present invention is obtained by polymerizing a vinyl aromatic hydrocarbon and a conjugated diene in a hydrocarbon solvent using an organolithium compound as an initiator. As the vinyl aromatic hydrocarbon used for the block copolymer used in the present invention, styrene, o-
Methylstyrene, p-methylstyrene, p-tert-
Butylstyrene, 1,3-dimethylstyrene, α-methylstyrene, vinylnaphthalene, vinylanthracene,
There are 1,1-diphenylethylene and the like, and particularly common one is styrene. These may be used alone or in combination of two or more. As conjugated dienes,
A diolefin having a pair of conjugated double bonds, such as 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 1,3- Examples thereof include pentadiene and 1,3-hexadiene, and particularly common examples include 1,3-butadiene and isoprene. These may be used alone or in combination of two or more.

The block copolymer mixture used in the present invention has a vinyl aromatic hydrocarbon content of 65 to 85% by weight, preferably 70 to 80% by weight, and a conjugated diene content of 35 to 15% by weight. , Preferably 30 to 20% by weight
It is. If the vinyl aromatic hydrocarbon content is less than 65% by weight and the conjugated diene content exceeds 35% by weight, the FE in the molded article increases, and conversely, the vinyl aromatic hydrocarbon content exceeds 85% by weight, If the diene content is less than 15% by weight, the elongation of the molded article is undesirably reduced.

The block copolymer used in the present invention is a block copolymer having at least two vinyl aromatic hydrocarbon polymer blocks and at least one polymer block mainly composed of a conjugated diene. One. (B) A- (BA) _n (b) A- (BA) _n
-B (c) A linear block copolymer represented by B- (AB) _{n + 1} or a general formula (d) [(AB) _k ] _{m + 2} -X (e) [( AB) _k
−A] _{m + 2} −X (f) [(BA) _k ] _{m + 2} −X (g) [(BA) _k
-B] a radial block copolymer represented by _{m + 2} -X (in the above formula,
A represents a polymer block composed of a vinyl aromatic hydrocarbon polymer. B is a polymer block mainly composed of a conjugated diene. The polymer block mainly composed of a conjugated diene of B is a polymer block of a conjugated diene alone and / or a copolymer block of a conjugated diene containing 50% by weight or more of a conjugated diene and a vinyl aromatic hydrocarbon. X represents a residue of a coupling agent or a residue of an initiator such as a polyfunctional organolithium compound. n, k and m are integers of 1 or more, generally 1 to 5. ).

The number average molecular weight of the block copolymer mixture used in the present invention is 50,000 to 300,000, preferably 70,000 to 20,000.
The range is 50,000. If the number average molecular weight is less than 50,000 or more than 300,000, it is not preferable because problems occur when recovering the block copolymer mixture and when molding. For the number average molecular weight, a calibration curve of the peak count number and the number average molecular weight of the monodisperse polystyrene was prepared from the monodisperse polystyrene for gel permeation chromatography (GPC) by GPC, and the standard method (for example, “gel chromatography < Basic edition> ”published by Kodansha).

The ratio of the weight average molecular weight to the number average molecular weight of the block copolymer mixture used in the present invention is 1.2 to 2.
5, preferably in the range of 1.2 to 2.3. If the ratio between the weight average molecular weight and the number average molecular weight is less than 1.2, the elongation of the molded article will decrease, and if it exceeds 2.5, the transparency of the molded article will deteriorate, which is not preferable. The vinyl aromatic hydrocarbon content of the block copolymer constituting the block copolymer mixture used in the present invention is in the range of the formulas (1) and (2) with an increase in the molecular weight in the range of 70,000 to 300,000. It has a composition distribution that continuously increases in the composition. If the vinyl aromatic hydrocarbon content of the block copolymer constituting the block copolymer mixture is less than the numerical value of the formula (1) in the molecular weight range of 70,000 to 300,000, the FE in the molded article increases, Exceeding the numerical value of (2) is not preferable because the transparency of the molded article deteriorates. The composition distribution of the block copolymer mixture of the present invention in the range of 70,000 to 300,000 is a mixture of several types of block copolymers, and the production method is not particularly limited, and block copolymers having different compositions are used. You may mix and manufacture in a solution or an extruder. In particular, a method of producing block copolymers having different compositions in the same polymerization vessel in the polymerization step is preferable. This is a method in which a monomer having a large L / D in a polymerization vessel is used to supply a monomer from the bottom under a low stirring condition to generate a concentration distribution in a polymerization system. The composition distribution of the block copolymer mixture in the range of 70,000 to 300,000 is determined by measuring the differential styrene content in the developing solution together with the molecular weight distribution using a differential refractometer and an ultraviolet spectrophotometer as a GPC detector. There are a method of obtaining the molecular weight, a method of obtaining the molecular weight of the block copolymer mixture by a conventional method, and the like. However, the method is not limited to these methods.

The styrene resin used in the present invention may be a non-rubber-modified styrene polymer or a rubber-modified polystyrene as long as the transparency is not impaired. Non-rubber modified styrene-based polymer, polystyrene, styrene-α-methylstyrene copolymer, acrylonitrile-styrene copolymer,
Styrene-methacrylate copolymer, styrene-
Although a maleic anhydride copolymer etc. are mentioned, what is especially preferable is a polystyrene and a styrene-n-butyl acrylate copolymer. These can be used alone or as a mixture of two or more.

The resin composition of the present invention has a weight ratio of (I) a block copolymer mixture to (II) a styrene resin of 5 /
95-70 / 30, preferably 10 / 90-60 / 40
It is. If the weight ratio of (I) and (II) is less than 5/95, the elongation of the molded article will decrease, and if it exceeds 70/30, the strength will decrease, which is not preferable. The resin composition of the present invention can be produced by any conventionally known compounding method. For example, open roll, intensive mixer,
Internal mixer, co-kneader, continuous kneader with twin-screw rotor, melt kneading method using a general kneader such as an extruder, a method of dissolving or dispersing and mixing each component in a solvent and then removing the solvent by heating are used. Can be

[0013] The resin composition of the present invention can contain optional additives as necessary. The type of additive is not particularly limited as long as it is generally used for compounding plastics. For example, glass fiber, glass beads, silica,
Inorganic reinforcing agents such as charcoal and talc, organic fibers, organic reinforcing agents such as cumarone indene resin, crosslinking agents such as organic peroxides and inorganic peroxides, pigments such as titanium white, carbon black and iron oxide, dyes, Examples include flame retardants, antioxidants, ultraviolet absorbers, antistatic agents, lubricants, plasticizers, other extenders, or mixtures thereof.

The resin composition of the present invention can be used as it is or colored and molded by the same processing means as ordinary thermoplastic resins, and can be used for various purposes. For example, it can be used for containers such as OA equipment parts, daily necessities, food, miscellaneous goods, light electric parts and the like by injection molding, blow molding and the like.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below, but they do not limit the scope of the present invention. The block copolymer mixtures used in the examples and comparative examples were produced as follows. [Block copolymer mixture A] 100 parts by weight of cyclohexane was added to 100 parts by weight of the block copolymer mixture in a polymerization vessel, and the temperature was raised to 60 ° C. Next, after adding 0.09 parts by weight of n-butyllithium, a cyclohexane solution of 6 parts by weight of 1,3-butadiene and 15 parts by weight of styrene was added at the same time, and the mixture was maintained for 30 minutes. Next, a cyclohexane solution of 24 parts by weight of 1,3-butadiene and 5 parts by weight of styrene was added at a constant flow rate to a temperature of 85 ° C.
After supplying for 5 minutes, it was maintained for 5 minutes. Next, styrene 10
A cyclohexane solution in parts by weight was supplied at a constant flow rate for 10 minutes, and then held for 3 minutes. Thereafter, methanol was added in a molar amount 0.2 times the amount of n-butyllithium, and the mixture was maintained for 3 minutes. Next, a cyclohexane solution of 40 parts by weight of styrene was supplied at a constant flow rate for 60 minutes, and then maintained for 5 minutes. Thereafter, in order to completely stop the polymerization, methanol was added in a polymerization reactor at a molar ratio of 0.9 times the amount of n-butyllithium, and as a stabilizer, 2-methoxy was added to 100 parts by weight of the block copolymer.
0.5 parts by weight of [1- (2-hydroxy-3,5-di-t-pentylphenyl) ethyl] -4,6-di-t-pentylphenyl acrylate and n-octadecyl 3-
(3,5-di-t-butyl-4-hydroxyphenyl)
After adding 0.3 parts by weight of propionate and 0.3 parts by weight of trisnonylphenyl phosphite, the block copolymer was recovered by removing the solvent. In addition, the concentration of the cyclohexane solution of styrene and 1,3-butadiene used in the polymerization is 30% by weight. Further, the block copolymer mixture A was polymerized under the condition of a stirring speed of 35 rpm using a polymerization vessel with L / D = 6. Table 1 shows the styrene content, number average molecular weight, molecular weight distribution (Mw / Mn) and composition distribution. The number average molecular weight was 40 ° C. in the developing solution, the column (manufactured by Phoenix) was 5 × 10 ⁶ Å, 5 × 10 ⁵ Å,
Measured using 5 × 10 ⁴ Å. FIG. 1 shows a molecular weight distribution curve and a composition distribution curve. [Block copolymer mixture BE] Using the same polymerization vessel as the block copolymer mixture A, the styrene content is the weight ratio of styrene to 1,3-butadiene, and the number average molecular weight is n-butyllithium. Mw / Mn and the composition distribution were adjusted by the monomer composition ratio, the amount of methanol added, and the number of stirring. Table 1 shows the styrene content, number average molecular weight, molecular weight distribution (Mw / Mn) and composition distribution. [Block copolymer mixture F] L of polymerization vessel used for polymerization
/ D = 2 and 3000 ppm in cyclohexane
Was polymerized under the same conditions as for the block copolymer mixture B except that tetrahydrofuran was used. Table 1 shows the styrene content, number average molecular weight, molecular weight distribution (Mw / Mn) and composition distribution.

[0016]

Examples 1 to 4 and Comparative Examples 1 to 3 According to the composition shown in Table 2, the extrusion temperature was 200 ° C. using a 40 mm sheet extruder.
To form a sheet having a thickness of 0.5 mm. Compounded GPP
S is Styron 685 (manufactured by Asahi Kasei Corporation), HIPS
Stylon 475D (manufactured by Asahi Kasei Corporation) was used. The transparency of the sheet (Haze: liquid paraffin is applied to the sheet surface, and measured according to ASTM D1003) is measured, and then the sheet is biaxially stretched to prepare a 0.05 mm thick film. To measure the breaking strength and the breaking elongation (tensile speed: 10 mm / min.
Except that it was measured according to JIS K-6872).
FE is operated continuously for 6 hours at a temperature of 230 ° C. by extruding a sheet having a thickness of 0.5 mm with a 40 mm sheet extruder, and the number of FEs of 1 mm or more per 150 cm ² of sheet area 5 minutes and 6 hours after the start of operation. Were evaluated by counting the difference (差: difference is 50 or less, ×: difference exceeds 50).

[0017]

[Table 1]

[0018]

[Table 2]

[0019]

The film using the resin composition of the present invention has good FE, and is excellent in transparency, breaking strength and breaking elongation. In particular, FE can be suitably used as a wrapping film, or as an extruded product such as a thin film or a laminated film for a foamed container or the like, by taking advantage of its good characteristics.

[Brief description of the drawings]

FIG. 1 shows a diagram of a molecular weight distribution curve and a composition distribution curve of a block copolymer mixture A.

Claims (1)

[Claims] 1. A block copolymer mixture comprising (I) a block copolymer having at least two vinyl aromatic hydrocarbon polymer blocks and at least one polymer block mainly composed of a conjugated diene. The polymer mixture has a vinyl aromatic hydrocarbon content of 65 to 85% by weight and a conjugated diene content of 35 to 15% by weight.
Weight percent, the number average molecular weight is 50,000 to 300,000 and the ratio of the weight average molecular weight to the number average molecular weight is in the range of 1.2 to 2.5, and the block copolymer constituting the block copolymer mixture is The polymer has a composition distribution in which the content of the vinyl aromatic hydrocarbon continuously increases in the range of the formulas (1) and (2) with the increase of the molecular weight in the range of 70,000 to 300,000. And (1) B = BO (−0.47 + 1.6 × 10 ⁻⁵ × M−)
5.5 × 10 ⁻¹¹ × M ² + 6.4 × 10 ⁻¹⁷ × M ³ ) (2) B = BO (0.28 + 1.3 × 10 ⁻⁵ × M−5)
6 × 10 ⁻¹¹ × M ² + 8.2 × 10 ⁻¹⁷ × M ³ ) (B: vinyl aromatic hydrocarbon content (% by weight) of the block copolymer having a molecular weight of M constituting the block copolymer mixture , BO: vinyl aromatic hydrocarbon content (% by weight) of the block copolymer mixture, M: molecular weight of the block copolymer constituting the block copolymer mixture) (II) a styrene resin; ) And (II)
A weight ratio of 5/95 to 70/30.